In the construction of conventional fixed geometry bearings of the fluid-wedge sliding surface type, the effects of loading on the surface is to reduce the fluid wedge thickness. This restricts replenishment of the lubricant.
In pivoting pad sliding surface bearings, the effects of loading on the surface of the pads and the lubricant viscous friction cause the fluid wedge of the lubricant to diverge in the direction of the movement of the rotating member with the result that the leading edge of the wedge tends to close and restrict this replenishment of the lubricant. This results from the direction of forces on the pads. This tendancy is reduced by the deformability of the pads under operating conditions. The result is bearings of limited load carrying capacity and with a limited ability to maintain a lubricant wedge thereby to prevent an operating condition known as "stick-slip."